Ink supplier for feeding a printer device

Abstract: An ink supplier for feeding a printer device with a fresh viscous conductive ink (4) comprises a housing with a chamber (312) in which the fresh conductive ink is contained and further comprises a tube (336) for providing a fluid connection between said chamber and an ink container chamber defined in the printer device proper. Furthermore, ink drive means are provided for forcing said conductive ink to flow towards said ink container chamber through said tube. Preferably, said ink drive means comprises a piston plate (334) slidably received in said chamber and an electrically actuated drive means for moving said piston plate. Preferably, said ink drive means comprises a support means for supporting the housing as well as compressed air feeding means for feeding the cylindrical chamber of said housing with compressed air.

Description: The present invention which is a divisional application from EP 94107395.9 relates in general to printer devices of the so-called "screen print type" which prints on an insulating base board an electric circuit through a screen plate. More specifically, the present invention is concerned with an ink supplier for feeding a printer device with a fresh viscous conductive ink. Description of the Prior Art Hitherto, various types of printer systems have been proposed and put into practical use particularly in the field of printed circuit manufacture. Some of them are of a type which employs a so-called "screen print type printer". This type printer device comprises generally a screen plate which is to be set on an insulating base board to be printed, and an ink squeezing device which runs on the screen plate while squeezing a given amount of viscous conductive ink onto the screen plate pressing the same against the insulating base board. With this, on the surface of the insulating base board, there is printed a desired circuit pattern of the conductive ink, which coincides with a perforated print pattern formed in the screen plate. The base board is then heated for fixing the printed circuit pattern. The screen plate is usually constructed of a stainless steel, silk or the like. For clarifying the present invention, some of conventional printer systems using the screen print type printer device will be described in brief. Japanese Patent Application 2-419135 shows an ink squeezing device usable in such printer devices. The ink squeezing device comprises generally a pair (viz., front and rear) of metal blades which have lower ends contactable with an upper surface of the screen plate, an ink container housing which is located between the paired blades and has an ink outlet opening through which a viscous conductive ink in the housing is squeezed toward the blades, and a shutter mechanism which opens the ink outlet opening when printing is needed and closes the opening when not needed. Only when the ink container housing is advanced for carrying out printing, the lower ends of the paired blades are brought into contact with the upper surface of the screen plate and one of the blades, which is the trailing one, serves as a squeezing blade. However, due to inherent construction, the printer device of the application has some drawbacks which are as follows. First, due to the repeated frictional contact carried out between the metal blades and the screen plate, one or both of them tend to have a marked abrasion within a shorter time, which thus shortens the life time of them. The lift time of them is further shortened when the ink contains pewter particles. In fact, during printing operation, the pewter particles get into a space between the blade tips and the screen plate and thus abrade them. In order to solve this drawback, a measure has been hitherto proposed in which plastic blades are used in place of the conventionally used metal blades. However, in this measure, due to the nature of the plastic which is the material of the blades, it is difficult to press the tips of the blades against the screen plate with a satisfied pressing force. By this reason, the pewter particles in the ink tend to separate from the flux of the ink during movement of the blades on the screen plate, resulting in that the pewter particles are left in the perforations of the screen plate thereby lowering the printing quality of the printer device. Of course, in order to obtain a satisfied pressing force with which the blades are pressed against the screen place, another measure may be thought out in which both the screen plate and the blades are constructed thicker in size. However, in this case, it becomes very difficult to form the screen plate with a very fine perforated print pattern. Furthermore, if the blade pressing force is extremely high, the perforations of the screen plate are easily deformed and finally broken. Furthermore, the printer device fails to provide the squeezing blade with an stable squeezing operation. In fact, during movement of the squeezing blade on the screen plate, the pressing force of the blade against the screen plate fluctuates markedly, which lowers the printing quality. Japanese Patent Application 2-419135 as mentioned hereinabove and Japanese Utility Model Application 3-77831 show a roller installed in the ink container housing of the printer, which has two functions, one being to stir up the viscous ink in the ink container housing when the ink outlet opening is closed and the other being to press out the ink when the ink outlet opening is open. However, repeated experiments and tests have revealed that a satisfied stirring of the ink is not obtained from such roller particularly when the viscosity of the ink is high. In fact, when treating such highly viscous ink, the stirring effect on the ink at a distance from the rotating roller is quite low. Some Japanese Patents and Patent Provisional Publications show a screen plate cleaning device for cleaning the screen plate, which functions to remove residual of ink left on the screen plate. Some are of a one-way trip type in which sweeping action is carried out once per each cleaning, and some are of a round trip type in which the sweeping action is carried out twice. However, due to the nature of the ink residual, the cleaning devices of these types fail to exhibit a satisfied cleaning performance. Other Japanese Patents and Patent Provisional Publications show an open type ink containing chamber defined by the ink container housing. That is, the chamber is constructed to be exposed to the open air. However, in this case, the ink in the chamber is easily affected by the surrounding air. In fact, under such open condition, the ink easily loses volatile components and thus the viscosity of the ink changes or increases instantly. Furthermore, the ink is easily oxidized, which changes the nature of the ink. Other Japanese Patents and Patent Provisional Publications show an ink supplier which feeds the printer device with viscous ink. However, due to inherent constructions, the ink suppliers shown by such documents fail to exhibit a satisfied ink supplying performance. EP-A-514 770 discloses a generic ink supplier having a cylindrical chamber closed by means of a coupling part screwed onto the cylindrical chamber. US-A-2, 070 206 likewise uses a cap screwed onto the cylindrical chamber. GB-A-599, 856 discloses a stenciling and/or coating machine. SUMMARY OF THE INVENTION It is an object of the present invention to provide an ink supplier for feeding a printer device with a fresh viscous ink, which comprises first means for defining a cylindrical chamber in which the fresh viscous ink is to be contained; tube means for providing a fluid connection between the cylindrical chamber and an ink container chamber defined in the printer device; and means for forcing the fresh viscous ink to flow towards the ink container chamber through the tube means. This object is achieved by the subject-matter of claim 1. Further embodiments of the invention are indicated in the subclaims. BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the inventive ink supplier will be described in conjunction with Figs. 5-11 whereas a printer device for which the inventive ink supplier is designed is illustrated in general in Figs. 1-4. In particular, Fig. 1 is a perspective view of a printer device into which the inventive ink supplier can be incorporated; Fig. 2 is a schematically illustrated side view of the printer device shown in Fig. 1; Fig. 3 is a view similar to Fig. 2, but showing a pair of blades dismantled from a major portion of the printer device; Fig. 4 is a side view of a unit consisting of two clamp assemblies which hold a squeezing blade of the printer device; Fig. 5 is a view similar to Fig. 2, but showing a measure for automatically feeding a viscous conductive ink to the printer device; Figs. 6 to 8 are schematic drawings showing one example for connecting an ink feeding tube from an ink supplier to the printer device; Fig. 9 is a sectional view of a first modification of the ink supplier which is also employable in the printer system; Fig. 10 is a view of the first modification, but showing an open condition of the same; Fig. 11 is a view taken from the direction of the arrow "E" in Fig. 12; and DETAILED DESCRIPTION OF THE INVENTION Referring to Figs. 1 to 4 of the drawings, there is shown a printer device with which the ink supplier of the present invention can be used. In the drawings, particularly in Figs. 1 and 2, denoted by reference "A" is a housing which has an ink container chamber 5 formed therein. The housing 5 has at its bottom portion a laterally extending ink outlet opening 3 through which a viscous conductive ink 4 (or pewter paste) is put out. A pair (viz., front and rear) of blades 2A and 2B are connected to the bottom portion of the housing "A" in a manner to locate therebetween the elongate outlet opening 3 and extend along the same. As will become apparent as the description proceeds, tips 2A' and 2B' of the blades 2A and 2B are forced to contact with an upper surface of a screen plate 1 which is arranged below the printer device. Positioned below the screen plate 1 is an insulating base board "P" on which a given circuit pattern is to be printed. A shutter mechanism (not shown) is incorporated with the housing "A", which functions to open the elongate outlet opening 3 when printing is needed and close the opening 3 when not needed. Although not shown in the drawings, a printer device mover is also associated with the housing "A" to move the housing "A" in fore-and-aft direction, that is, in the direction of arrows "X" and "Y" in Fig. 1. As will become apparent as the description proceeds, only when the housing "A" is moved in the direction of the arrow "X" for carrying out the printing, one (viz., the trailing blade 2B) of the blades 2A and 2B serves as a squeezing blade, as will be understood from Fig. 2. As is seen from Figs. 1 and 2, the housing "A" comprises a pair of side walls 6A and 6B, a rear wall 7 having both ends secured to the side walls 6A and 6B, a front wall 8 pivotally held at its upper portion by the side walls 6A and 6B and a lid 9 detachably mounted to upper portions of the four walls 6A, 6B, 7 and 8. Thus, the housing "A" has a chamber 5 defined by the four walls and the lid 9. Designated by numeral 10 in Fig. 1 is a pivot shaft which is held by the side walls 6A and 6B for pivoting the front wall 8. As is seen from Figs. 2 to 4, the fixed rear wall 7 has a lower portion which extends obliquely downward toward a lower portion of the pivotal front wall 8. The rear wall 7 has a stepped inner surface 7A. The pivotal front wall 8 has a lower portion 8A which extends obliquely downward toward the lower portion of the rear wall 7. As is seen from Fig. 2, the lower portion 8A has an inclined inner surface 8B which extends to an upper vertical inner surface 8C of the front wall 8 through a curved inner surface 8B'. Designated by numeral 8D is an inclined lower surface of the lower portion 8A, which is generally perpendicular to the inclined inner surface 8B. As shown, the front blade 2A is secured to the pivotal front wall 8 and the rear blade 2B is secured to the rear wall 7. These front and rear blades 2A and 2B extend obliquely, that is, downward rearward with respect to the direction of the arrow X. The pivotal front wall 8 is actuated by a shutter mechanism (notshown). Each blade 2A or 2B is constructed of a resilient metal, such as spring steel and the like. Each blade 2A or 2B has a smoothly rounded tip 2A' and 2B' for minimizing the frictional force produced when slidably engaged with the screen plate 1. Preferably, the thickness of each blade 2A or 2B is smaller than 0.5 mm. If the blade is made of a spring steel, the thickness of the blade can be reduced to 0.1 to 0.05 mm. As is shown in Fig. 3, in order to mount the front blade 2A to the pivotal front wall 8, a first clamp assembly 14 is used, which comprises an outer elongate mounting member 11 of generally L-shaped cross section, an inner elongate mounting member 12 of generally triangular cross section and a plurality of connecting bolts 13. Before being mounted to the front wall 8, the front blade 2A is tightly clamped by the clamp assembly 14, as shown in Fig. 3, and then the clamp assembly 14 is secured to the inclined lower surface 8D of the front wall 8 by screwing the connecting bolts 13 into associated threaded bores (no numerals) formed in the front wall 8. As is seen from Fig. 2, when the clamp assembly 14 is properly secured to the front wall 8, one surface 11A of the outer elongate mounting member 11 is flush with the inclined inner surface 8B. As is shown in Fig. 3, in order to mount the rear blade 2B to the fixed rear wall 7, a second clamp assembly 18 is used, which comprises an outer elongate mounting member 15 of generally L-shaped cross section, an inner elongate mounting member 16 of generally rectangular cross section and a plurality of connecting bolts 17. Before being mounted to the rear wall 7, the rear blade 2B is tightly clamped by the clamp assembly 18 and then the clamp assembly 18 is secured by means of the connecting bolts 17 to a third clamp assembly 19 which has been secured to the fixed rear wall 7. As shown, the third clamp assembly 19 is neatly set in a recess defined by the stepped inner surface 7A of the rear wall 7. Of course, if desired, as is understood from Fig. 4, before being mounted to the rear wall 7, the two clamp assemblies 18 and 19 may be coupled to constitute one unit 20, and then the unit 20 is secured to the rear wall 7 by means of a plurality of connecting bolts 19a. As shown, the connecting bolts 19a pass through bores formed in the rear wall 7 and are engaged with threaded bores formed in an inner elongate member 27 of the third clamp assembly 19. As is shown in Fig. 4, the third clamp assembly 19 comprises an outer elongate member 29 of generally L-shaped cross section, the inner elongate member 27 of generally rectangular cross section and the connecting bolts 19a. The third clamp assembly 19 has a first partition blade 28 of steel clamped thereby, which extends into the chamber 5 of the housing "A" for the purpose which will be described hereinafter. As will be understood from Figs. 2 and 3, upon assembly, shorter walls 15A and 29A of the outer elongate mounting members 15 and 29 face to an inclined inner surface which includes the surface 11A of the outer elongate mounting member 11 and the inclined inner surface 8B. It is to be noted that when the pivotal front wall 8 is pivoted clockwise in Fig. 2 to a given angular position, the surface 11A of the first clamp assembly 14 connected to the front wall 8 becomes in contact with the surface 15A' of the shorter wall 15 of the second clamp assembly 18. Under this condition, the ink outlet opening 3 is closed. As is seen from Fig. 2, denoted by numeral 30 is a second partition blade of steel which extends into the chamber 5 of the housing "A" from the fixed rear wall 7. That is, the second partition blade 30 is bolted to a mounting block 31 secured to an inner surface of the rear wall 7. Leading ends 28A and 30A of the first and second partition blades 28 and 30 are pressed against an outer cylindrical surface of an elongate roller 32 which is rotatably held in the chamber 5 of the housing "A". The roller 32 is coaxially mounted on a rotating shaft which is rotatably held by the side walls 6A and 6B of the housing "A". The shaft has a gear meshed with an output gear driven by a reversible electric motor. Thus, upon enegization of the motor, the roller 32 is rotated in the chamber 5. Thus, as is seen from Fig. 2, a part 32A of the cylindrical outer surface of the roller 32, the partition blade 28, the shorter wall 29A, the shorter wall 15A and the second blade 2B constitute a second guide wall G2. While, the upper vertical inner surface 8C, the curved inner surface 8B', the inclined inner surface 8B, the surface 11A and the first blade 2A constitute a first guide wall G1. That is, between the first and second guide walls G1 and G2, there is defined a narrow passage 33 which extends from the ink containing chamber 5 toward the first and second blades 2A and 2B. Accordingly, when, under rotation of the roller 32 in the direction of the arrow "R" (see Fig. 2), the front pivotal wall 8 is pivoted to open the outlet opening 3 by the shutter mechanism "B", the viscous conductive ink 4 in the chamber 5 is forced to flow downward in and along the narrow passage 33 and discharged onto the screen plate 1. While, when the roller 32 is rotated in a reversed direction, the viscous ink 4 is prevented from making a downward flow in the narrow passage 33 due to interruption by the roller 32. Thus, when the reversed rotation of the roller 32 starts just before the closing of the outlet opening 3, undesired leakage of the ink 4 from the outlet opening 3 is assuredly prevented. If desired, a speed changer may be arranged between the motor "M" and the roller 32. Fig. 5 shows another measure for automatically feeding a viscous conductive ink 4 to the printer device. That is, in this measure, first and second conductive members 350 and 352 are placed at vertically spaced positions in the ink container chamber 5 of the printer device. These two conductive members 350 and 352 are connected to a controller 354. That is, when the level of the ink 4 falls below the first conductive member 350, the electric resistance between the two conductive members 350 and 352 changes or increases, which is sensed by the controller 354. Figs. 6 to 8 show one example for connecting the ink feeding tube 336 to the printer device. As will be seen from Figs. 6 and 8; the tube 336 is connected to the ink inlet opening 42 of the fixed rear wall 7 by means of a connecting nut 360. Behind the rear wall 7, there is installed an elongate block 362 which is formed with an elongate recess 364 having a semicircular cross section. When the block 362 is properly fixed to the rear wall 7 by means of bolts, the ink inlet opening 42 is exposed to the recess 364 of the block 362. The block 362 is formed with a plurality of parallel passages 366 each extending from the recess 364 to the ink container chamber 5 (see Fig. 2). Each passage 366 has a threaded bore (no numeral) which extends vertically therefrom. As is best understood from Fig. 6, the threaded bores receive therein respective adjusting screws 368. Thus, by turning the adjusting screws 368 in the threaded bores, the area of each passage 366 can be adjusted. Thus, the amount of ink 4 fed to the ink container chamber 5 can be controlled or adjusted by the adjusting screws 368. That is, the viscous ink 4 can be evenly stored in the ink container chamber 5. If desired, in place of the elongate block 362, a slit cylinder may use used for achieving the even scoring of the ink 4 in the ink container chamber 5. That is, the slit cylinder (viz., a cylinder member having a longitudinally extending slit formed therethrough) is rotatably disposed behind the fixed rear wall 7 below the ink inlet opening 42, and an elongate chamber member is arranged to cover the slit cylinder. The elongate chamber member has at its lower wall an elongate opening exposed to the ink container chamber 5 of the printer device. The slit cylinder is rotated stepwisely by a suitable electric motor. For a given time, the ink 4 is fed to the chamber member with the slit cylinder keeping its close position. With this, the chamber member is filled with the ink 4. Then, the slit cylinder is turned to its open position causing the ink 4 to flow down through the slit into the ink container chamber 5 of the printer device. Referring to Figs. 9 to 11, there is shown a preferred embodiment of the ink supplier according to the invention which is employable in the printer system. As is best understood from Fig.9, the ink supplier comprises a circular holder plate 400 which has a circular opening with which a bottom open end of the cartridge 312 is mated. Another circular plate 402 is pivotally connected to holder plate 400 by means of a known hinge mechanism. The pivotal plate 402 thus has two angular positions, one being a close position as shown in Fig. 9, wherein the pivotal plate 402 lies on the holder plate 400 and an open position as shown in Fig. 10 wherein the pivotal plate 402 is released from the holder plate 400. The pivotal plate 402 is equipped with a grip 404 and formed with an opening 406. First and second annular seals 408 and 410 are secured to inner surfaces of the two plates 400 and 402 respectively. Thus, when the pivotal plate 402 is in the close position as shown in Fig. 9, the opening 406 is communicated with the bottom open end of the ink cartridge 312. Designated by numeral 420 is a bolt for detachably connecting the pivotal plate 402 to the holder plate 400. A valve 412 is mounted on the pivotal plate 402 which has an outlet connected to the opening 406 through a pipe 414 and an inlet connected to a compressed air source 416 (or compressor) through a tube 418. The valve 412 has a control button 412a for selectively opening and closing a communication between the inlet and outlet of the valve 412. Thus, when, with the pivotal plate 402. assuming the close position as shown in Fig. 9, the control button 412a is pushed, the compressed air from the compressed air source 416 is fed into the bottom open end of the cartridge 312. With this, the piston plate 334 in the cartridge 312 is forced to move leftward while pushing the viscous ink 4 into the printer device through the tube 336.

Claims: An ink supplier for feeding a printer device with a fresh viscous conductive ink (4), comprising: a housing having a cylindrical chamber (312) in which the fresh viscous conductive ink (4) is contained; a tube (336) for providing a fluid connection between the cylindrical chamber (312) and an ink container chamber provided in said printer device; ink drive means for forcing said fresh viscous conductive ink (4) to flow toward said ink container chamber through said tube (336), which comprises a support plate (400) for supporting said cylindrical chamber (312), and compressed air feeding means (416) for feeding compressed air into the cylindrical chamber (312) of said housing, characterised in that, the compressed air feeding means (416) is connectable to the cylindrical chamber (312) via a plate (402) which is pivotally connected to the support plate (400) so as to close or to open a bottom open end of the cylindrical chamber (312) wherein the support plate (400) has an opening to give access to the cylindrical chamber (312). Ink supplier according to claim 1, characterised in that the opening of the support plate (400) matches with the bottom open end of the cylindrical chamber (312). Ink supplier according to claim 1, characterised in that the plate (402) which is pivotally connected to the support plate (400) has an opening (406) smaller than the opening of the support plate (400) through which the compressed air flows into the cylindrical chamber (312). Ink supplier according to claim 1, characterised in that the plate (402 has an annular seal (410) that tightly seals the plate (402) and the support plate (400), if the plate (402) is in its closed position. Ink supplier according to claim 1, characterised in that the support plate (400) has an annular seal (408) that tightly seals the plate (402) and the support plate (400) if the plate (402 is in its closed position. Ink supplier according to claim 1, characterised in that a valve (412) is provided between the plate (402) and the compressed air feeding means (416) that controls the supply of compressed air into the cylindrical chamber (312). Ink supplier according to claim 1, characterised in that a grip (404) is provide on the plate (402 to facilitate the change from the closed to the open position of the plate (402) and vice versa. Ink supplier according to claim 1, characterised in that a piston plate (334) is provided in the cylindrical chamber (312) that transmits a pressure caused by the compressed air onto the ink (4), thereby pushing the ink out of the cylindrical chamber (312). Ink supplier according to claim 1, characterised in that the pivotal plate (402) is securable to the support plate (400) in the closed position by means of a bolt (420).

Inventors: TANI OKIE, TANI, OKIE
Applicants: TANI DENKI KOGYO KK, TANI ELECTRONICS INDUSTRY CO., LTD.
Application year: 1994
Main classification: B41F15
IPC codes: B41F31, B41F15, H05K3